Thals, Anaximander, Anaximens, Heraclitos, and Anaxagoras were all natives of Ionia, and were the earliest of the Greek philosophers. They tried to prove that all created things spring from one principle; Thals said it was water, Anaximens thought it was air or gas, Anaxagoras that it was atoms, Heraclitos maintained that it was fire or caloric, while Anaximander insisted that the elements of all things are eternal, for ex nihilo nihil fit.